Food container



1964 R. A. FARRELL ETAL 3,158,491

FOOD CONTAINER Filed Feb. 26, 1965 2 Sheets-Sheet l A H G ua IN VEN TORS' o E r A. F RRELL e'o R s v Jounousm Arrow 5v 1954 R. A. FARRELL ETAL 3,153,491

FOOD CONTAINER Filed Feb. 26, 1963 2 Sheets-Sheet 2 INVENTORS ROBERT A. FARRELL GEORGE SKOWRONSKI A FOR/V5) United States Patent 3,153,491 F9013 CGNTAINER Robert A. Farrell, Menasha, and George V. Skowronslsi, Neenah, Wis, assignors to American Can Company, New York, N.Y., a corporation of New Jersey Filed Feb. 26, 1953, Ser. No. 261,561? 7 Claims. (Cl. 99-471) This invention relates to a heat-sealed leakproof package. More specifically, the invention relates to a hermetically sealed package, having an opening means therein, for the packaging of prepared foods, such as potato salad, sandwich spreads, and frozen foods.

In the food merchandising industry it is particularly important to have packages which are hermetically sealed, have sufllcient rigidity of construction for stacking during shipment and can be readily opened. In addition, if the packages are to be displayed, it is advantageous to have. a window in the top for easy viewing of the contents without destroying the airtight seal and tamperproofness. Furthermore, it is important that the package components be shipped in stacked and nested condition to the product packager to save storage space prior to the formation of the completed package.

The package is formed from'a rigid receptacle portion, such as a tapered plastic tray, having a bottom and continuous side with an outwardly extending continuous flange around the entire perimeter at the upper edge thereof and a separate cover portion which is heat-sealed to the upper surface of said flange after the receptacle portion is filled. The cover portion comprises frangible material, such as paperboard, having a heat-scalable coating, such as polyethylene, on the inner surface thereof. Lines of weakness in the frangible material define both a removable panel providing a window and opening means to gain access to the contents of the package. The polyethylene, in addition to providing a sealing medium, serves to provide a liquid impermeable closure.

The particular objects and advantages of the invention will be made clear from the following description in connection with the accompanying drawings, in which:

FIGURE 1 is a diagrammatic representation of a method for continuously converting suitable materials into blanks for use as cover portions of food packages,

FIGURE 2 is a top view of one of the blanks produced according to our method,

FIGURE 3 is a bottom view of the blank of FIG- URE 2,

FIGURE 4 is a perspective view of a food package made according to the present invention,

FIGURE 4A is a partial sectional view taken along line lA-4A of FIGURE 4 showing the superposed layers at the perimeter of the package,

FIGURE 5 is a perspective view of the food package having the window panel removed,

FIGURE 6 is a perspective view of the food package having the opening means partially removed, and

FIGURE 7 is a perspective view of the food package having the opening means and window portion removed and the contents exposed.

Referring more particularly to FIGURE 1, there is shown a continuous method for converting a frangible material, i.e., paperboard, and a heat-scalable material, i.e., polyethylene, into composite blanks, such as the one depicted in FIGURES 2 and 3. Initially, a web of paperboard 10 is unwound and the leading edge threaded through the rolls in the manner shown in FIGURE 1. The paperboard is fed through applicator roll 11 and back-up roll 12, denoting generically a multi-color press, for printing the web with any desired indicia. The applicator roll 11 transfers the ink from an ink bath 13. After passing through the rolls l1 and 12, a pattern of 3,158,491 Patented Nov. 24, 1964 release agent is applied to the unprinted side of the blank agent is applied on one side of the web, while the print-' ing is applied to the other. In the composite blank, shown in FIGURE 3, the area covered by the release agent is indicated by the stippling. Any suitable means, such as a gravure'cylinder, may be employed for applying the release agent. A variety of release agents may be employed, the choice being determined by the heat-scalable material to be applied to the paperboard. For instance, when polyethylene is the material to be applied to the web, the following coatings are particularly desirable since they give high gloss and clarity to the polyethylene as well as excellent release properties to the paperboard:

(l) A solution of 60% xylene and 40% of a mixture of 98% DOW PS-3 polystyrenea low molecular weight polystyrene produced by the Dow Chemical Company, and 2% Slipezea fatty acid amine commercial release agent produced by Fine Organics, Inc.

(2) A solution of 86% blended, volatile organic solvents and 14% /2 Second Butyrate-a cellulose acetatebutyrate produced by Eastman Chemical Co.

The printed and coated web 10 then passes through a first cutting station comprising tensioning rolls 19, 25, eccentric synchronizing rolls 20, 24 for feeding the web to and from the cutting means 22 and tension rolls 21 and 23 immediately adjacent the cutting means. As the web is advanced through the cutting station, theeccentric synchronizing rolls 20, 24 facilitate intermittent starting and stopping of the web coordinated with the reciprocating action of the cutting means 22. The first cut produces all the cutting and creasing lines impressed in the blank exclusive of the outer edge, as shown in FIGURES 2 and 3. Included in the firstcutting and creasing step are partial cut line 40, which extends inward from the printed side only about halfway through the thickness of the paperboard, cut lines 41, angled lines of weakness 42, score line 45 and cut lines defining cut out areas 54 and 55.

The web 10 next passes over idler roll 25 and around drum 28. An extruder 26 positioned above the nip formed by idler roll 25 and drum 28 extrudes a film of polyethylene 61 onto the traveling web on the side having the release coating thereon. All of the cut lines are covered and sealed by the extruded coating material. The thickness of the extrusion coating, generally between one and two mils, varies with the material employed and with the degree of strength and protection required.

The composite web then travels over idler roll 29, feed rolls 30, 31, constant tension roll 32 and idler roll 33 into a second cutting means 34 which separates the web into composite blanks A shown in FIGURES 2 and 3. As the blanks leave the second cutting means 34, they are transferred to an endless moving outfeed belt 35 rotating around pulley 36 and then removed for packing. The blanks are stacked, boxed and shipped to the product packager for use with receptacle portions to form completed packages.

The composite blank A comprising paper board and polyethylene is divided by partial out line 40, cut lines 41, angled cut lines 42 and score line 45 into edge panel 50, tear strip 51, center panel 52 and pull tab 53. A tearaway element 51a, shown in FIGURES 2 and 4, is defined by partial cut line 40 and the portions of angled cut lines 42 parallel to said partial cut line 40. Edge 4.3 of the center panel 52 and cut lines 41 define an area 54 in which the paperboard has been removed to facilitate removal of the center panel 52 for display purposes. Similarly the free edge of pull tab 53 and cut lines 41 define an area 55 in which the paperboard has been removed to facilitate grasping of the pull tab 53 for removal of the tear strip. As is readily apparent from FIGURE 3, the polyethylene layer is coextensive with the perimeter of the paperboard.

The food package is formed by first filling a receptacle portion such as a tapered tray 60 shown in FIGURE 4, with the commodity to be packaged. The receptacle portion comprises a bottom panel and continuous side walls connected therewith. The upper edges of the side walls terminate in a continuous outwardly extending flange portion 60a which is preferably smooth and fiat at its upper surface and preferably extends in a substantially horizontal plane. Trays made from materials, such as high density polyethylene, are particularly suitable since they provide a rigid construction at an economical price and can be heat-sealed readily to a variety of materials, such as high or low density polyethylene. After the tray 69 is filled with product 79 (see FIGURES -7), the blank A, which is the cover, is placed on the tray. The outer edge of the outwardly extending flange portion 60a of the tray, as shown in FIGURE 4A, coincides with the outer edge of the blank or cover. The cover is placed with the polyethylene layer 61 in contact with the flange portion 60a. Heat and pressure are then applied around the entire perimeter of the cover portion to heat-seal the polyethylene layer 61 and the flange portion 6011 together. Upon completion of the sealing step the contents of the package are hermetically enclosed. The completed package is shown in FIGURE 4.

The center panel 52 can be removed for the displaying of the contents '70 by grasping at the edge 43 and pulling upward to detach along lines of weakness-41. Because of the release agent on the inner surface of the cover portion (see the stippled area of FIGURE 3), the center panel 52 can easily be removed without disturbing the underlying layer of polyethylene (see FIGURE 5). In addition, the polyethylene exposed has a high gloss and high degree of clarity due to the particular release agent employed. The completed package having the center panel 52 removed is shown in FIGURE 5.

The package is opened and the contents exposed by grasping the pull tab 53 and lifting and pulling the tear strip 51 back upon itself, as shown in FIGURE 6. The extruded polyethylene 61 adheres to the underside of the tear strip 51 and is removed along with the tear strip. After completely removing the tear strip 51 the contents of the package are exposed, as shown in FIGURE 7. The relationship between the thickness of the paperboard and the thickness of the polyethylene is governed by the need for the polyethylene to tear before the paperboard breaks or peels back thereby preventing opening. The portions between the individual angled cut lines 42 tend to remain attached to the tear-away element 51a: when the tear strip 51 is removed causing peeling of the upper surface of the cover. Partial cut line 40 limits the extent of outward peeling so that tear element 51a is uniformly removed down to about one-half the thickness of the paperboard while the remainder of the cover remains intact.

It is obvious that materials other than those described previously may be employed. For instance, the receptacle portion may be made of polystyrene or polypropylene and the heat-scalable material may be any of a variety of coated cellophane. The choice of the particular materials will be dictated by the properties of each. In order to insure a hermetically sealed package, the heat-scalable material on the cover must readily seal to the receptacle portion. Also the release agent should not cloud the heatsealable material so as to detract from the appearance of the window for display purposes. The opening means will not function properly unless the degree of adhesion between the heat-scalable material and the frangible material of the cover is sufficient to prevent their separation when the tear strip is removed.

If desired, the receptacle portion may be made of coated paperboard and have a foil lining on the inner surface. Then, after opening, the package can be immediately inserted in the oven and the contents baked in the receptacle portion.

The present invention provides a tamperproof hermetically sealed package, which can readily be stacked for shipping purposes. The package provides a window panel which may be removed for display purposes and also a tear strip which provides ready access to the contents. Since the frangible cover material never contacts the contents in the completed closed package, there is no wicking of the product. The receptacle may in some instances be used to bake the contents of the package without the necessity of employing a separate vessel. The use of a preformed plastic tray for the receptacle portion reduces the equipment required by the packager for setting up cartons from blanks. In addition to providing an attractive appearance to the completed package, the tray can be reused by the consumer for storage.

It is to be understood that the size and the shape of the package and the materials from which it is formed may be varied in numerous ways by those skilled in the art without departing from the spirit of the invention.

We claim:

1. A tamperproof sealed package comprising a leakproof receptacle portion having a bottom panel and side walls connected to said bottom panel, and a continuous outwardly extending flange connected to the upper edges of said side walls; a product contained in said receptacle portion; and a cover substantially coextensive with the outer perimeter of said flange closing said receptacle portion, said cover comprising a frangible material sealed to said flange by a layer of liquid impermeable heat-activated coating extending over substantially the entire inner sur-- face of said material, said frangiblematerial having a tear strip with a pull tab defined by a pair of spaced substantially parallel lines of weakness positioned adjacent and inwardly of the flange of the receptacle portion.

2. The package of claim I wherein said receptacle portion is a tapered plastic tray.

3. The package of claim 1 wherein the frangible material is paperboard and the heat-activated coating is polyethylene.

4. A tamperproof sealed package comprising a receptacle portion having a bottom panel and a continuous side wall attached to said bottom panel along the bottom edge of said side wall, and a continuous substantially outwardly extending flange integral with the upper edge of the side wall; a product contained in said receptacle portion; and a cover substantially coextensive with the outer perimeter of said fiange closing said receptacle portion, said cover comprising a frangible material sealed to said flange by a layer of heat-activated coating extending over substantially the entire bottom surface of said material, said frangible material having a removable center panel and a tear strip with a pull tab defined by a pair of spaced substantially parallel closed lines of weakness positioned inwardly of said flange, the bottom surface of the center panel having a release coating thereon to prevent adhesion of the layer of heat-activated coating to the center panel.

5. The package of claim 4 wherein said receptacle portion is a tapered plastic tray.

6. The package of claim 4 wherein the frangible material is paperboard and the heat-activated coating is polyethylene.

7. A tamperproof sealed package comprising a tapered plastic tray having a continuous substantially outwardly extending flange depending from the upper edge of the sides of said tray; a product contained in said tray; and a cover substantially coextensive with the outer perimeter of said flange closing the top of said tray, said cover comprising paperboard sealed to said flange by a layer of extruded polyethylene extending over substantially the entire inner surface of said paperboard, said paperboard having a removable center panel and a tear strip provided g with a pull tab defined by a pair of spaced substantially 2,677,318 5/54 Torudd 931.3 parallel closed lines of Weakness positioned inwardly of 2,834,686 5/58 Reuman 99171 said flange, the inner surface of the center panel having 2,999,948 7/61 Z khei a release coating thereon to prevent adhesion of the l yer 2,996,236 8/61 Barr 229-48 of poly yl to h center p 5 3,054,680 9/62 Mennen 99-171 References Cited by the Examiner 3069273 12/62 Wayne 229-51 X UNITED STATES PATENTS GEORGE O. RALSTON, Primary Examiner. 1,850,493 3/32 Brewer 93-13 FRANKLIN T. GARRETT, Examiner.

2,554,160 5/51 Von Gunten 229-51 X 10 

1. A TAMPERPROOF SEALED PACKAGE COMPRISING A LEAKPROOF RECEPTACLE PORTION HAVING A BOTTOM PANEL AND SIDE WALLS CONNECTED TO SAID BOTTOM PANEL, AND A CONTINUOUS OUTWARDLY EXTENDING FLANGE CONNECTED TO THE UPPER EDGES OF SAID SIDE WALLS; A PRODUCT CONTAINED IN SAID RECEPTACLE PORTION; AND A COVER SUBSTANTIALLY COEXTENSIVE WITH THE OUTER PERIMETER OF SAID FLANGE CLOSING SAID RECEPTACLE PORTION, SAID COVER COMPRISING A FRANGIBLE MATERIAL SEALED TO SAID FLANGE BY A LAYER OF LIQUID IMPERMEABLE HEAT-ACTIVATED COATING EXTENDING OVER SUBSTANTIALLY THE ENTIRE INNER SURFACE OF SAID MATERIAL, SAID FRANGIBLE MATERIAL HAVING A TEAR STRIP WITH A PULL TAB DEFINED BY A PAIR OF SPACED SUBSTANTIALLY PARALLEL LINES OF WEAKNESS POSITIONED ADJACENT AND INWARDLY OF THE FLANGE OF THE RECEPTACLE PORTION. 